Heat system for compartment of a train car

ABSTRACT

A system for heating a compartment of a rail car having a heat-generating engine with a cooling-water system has a heating element, a fan for passing a stream of air over the heating element and into the compartment, and a radiator in the cooling-water system and in the stream of air downstream of the fan.

FIELD OF THE INVENTION

The present invention relates to a heating system. More particularly this invention concerns a heater for a passenger or driver compartment of a train car.

OBJECT OF THE INVENTION

The object of the present invention is to use the generated waste heat of a railroad car for heating the passenger compartment and/or the driver's cab of the car.

SUMMARY OF THE INVENTION

A system for heating a compartment of a rail car having a heat-generating engine with a cooling-water system has according to the invention a heating element, a fan for passing a stream of air over the heating element and into the compartment, and a radiator in the cooling-water system and in the stream of air downstream of the fan.

The cooling water heat exchanger operates independently from the coolant circuit of the heating device and supplies additionally or by itself heat for heating the passenger compartment and/or the driver's cab. The feed air fan of the heating device is responsible for transporting the heated air into the vehicle.

The heating system further has according to the invention a heat pump having a compressor, a first heat exchanger, an expansion valve, and a second heat exchanger connected in a closed circuit through which a compressible heat-exchange fluid is circulated by the compressor in one direction when operating in heating mode and in an opposite direction when operating in cooling mode. One of the heat exchangers according to the invention forms the heating element.

According to another feature of this invention means is provided means for extracting air containing waste heat from the rail car and passing it through the other of the heat exchangers. In doing so, the waste heat is not immediately transferred to the feed air flow. Rather, the waste heat that is transported via the waste-air stream is passed to the evaporator of the heat pump, and the thermal energy is initially transferred from there to the cooling circuit of the heat pump. As a result, the temperature level of the heat pump is increased even further.

Advantageously, the cooling water heat exchanger is located in the feed air flow upstream of the condenser. If is insufficient exhaust heat from the engine is available, the heat pump is operated to heat the air preheated by the cooling water heat exchanger to the desired temperature by means of the condenser of the heat pump.

According to the invention it is also possible for the heating device to be an electric heating register.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a schematic diagram of the heating system of this invention; and

FIG. 2 is a view like FIG. 1, but with an additional air line connected to the evaporator of the heat pump and through of which the waste heat is vented from the rail car.

SPECIFIC DESCRIPTION OF THE INVENTION

As seen in FIG. 1, a heat pump 1 has a compressor 8 that compresses a gaseous heat-exchange fluid and feeds it under high pressure when operating as a heater to an internal heat exchanger 2 acting as a condenser. A fan 6 blows air through the condenser 2 so that heat from the compressed heat-exchange agent is transferred to the passing air that then is fed into a passenger compartment 14 while simultaneously liquefying the heat-exchange fluid.

While still a liquid and pressurised, the heat-exchange fluid passes through an expansion valve 10 that abruptly drops its pressure. This not only results in a temperature reduction of the heat-exchange fluid, but also gasifies it. The gasified and cooled heat-exchange medium then passes through an external heat exchanger 3 acting as evaporator. In the evaporator, the heat-exchange agent is warmed by ambient air passed through it by a fan 7 until it is completely evaporated.

A separate heat exchanger or radiator 4 is provided immediately upstream of the internal heat exchanger 2 in the direction of air flow through it from the fan 6 to receive heat therefrom, that is between the upstream side of the condenser 2 and the fan 6. This radiator 4 is connected in the cooling-water system used to heat the two electric motors 5 of the rail car 15. Thus the water pumped through these motors 5 to cool them is pumped through the radiator 4. The waste heat from the motors 5 at least is therefore also used to heat the condenser 2 and the rail-car compartment. The waste heat is utilized as a result of the integration of the separate cooling water heat exchanger 4 that operates independently from the circuit of the heat pump 1. In the motor-cooling circuit, standard engine cooling liquids, typically mainly water, are used as the heat-exchange fluid or medium to carry energy.

In this system, cool fresh or cool mixed air is sucked in by the fan 6 and is passed through both heat exchangers 2 and 4. If sufficient waste heat from the engine is available, the air can be heated only via the cooling water heat exchanger 4 and can be blown into the passenger compartment 14. The heat pump 1 and thus the internal heat exchanger 2 acting as condenser can be switched off and therefore remain without function. The cooling water heat exchanger 4 is provided in the feed air flow upstream of the condenser 2. The reason for this is that, if not enough waste heat from the engine is available, the heat pump 1 is also operated in order to heat the air preheated by the cooling water heat exchanger 4 to the desired temperature before entering the condenser 2.

If no engine waste heat is available at all, the heat pump 1 takes over the heating of the feed air on its own by the condenser 2, and the cooling-water heat exchanger 4 remains without function.

In addition, if the operating mode of the heat pump is reversed to air conditioning, the cooling water heat exchanger 4 can also be used as an anti-freezing protector for the internal heat exchanger 2 in this case serving as evaporator during air conditioning operation. As a result, the use of an energy-intensive bypass as anti-freezing protection is not necessary.

All of these processes are connected to a common controller 9.

In the embodiment according to FIG. 2, in heating mode a stream 12 of hot air carrying waste heat is passed through the heat exchanger 3 of the heat pump 1, so its thermal energy is initially transferred to the heat-exchange medium in the heat pump 1, as a result of which the temperature level is increased is even further.

The waste heat of many subsystems (traction converter, auxiliary converter, brake resistor) can be used. Apart from the existing waste heat, also a stream 11 of warm air from the compartment 13 of the rail car 14 can be used and its thermal energy can be recovered. Also a combination from both sources is possible.

If the heat pump 1 is switched to air conditioning operation, the air ducts that carry the waste heat to the outside heat exchanger 3 during heat-pump operation, may be provided with flaps 13, so that during air conditioning operation, the waste heat does not go to the outside heat exchanger or condenser 3.

As a function of the thermal energy that can be supplied to the heat pump, energy-intensive anti-freezing protection can also be overridden or greatly reduced when ambient temperatures are low.

A large number of modifications are possible within the scope of the invention. For example, as was explained at the beginning, instead of the heat pump 1 or the condenser 2 thereof an electric heater may be provided, e.g. an electrically powered resistive heating coil. 

I claim:
 1. A system for heating a compartment of a rail car having a heat-generating engine with a cooling-water system, the system comprising: a heating element; a fan for passing a stream of air over the heating element and into the compartment; and a radiator in the cooling-water system and in the stream of air downstream of the fan.
 2. The heating system defined in claim 1, further comprising: a heat pump having a compressor, a first heat exchanger, an expansion valve, and a second heat exchanger connected in a closed circuit through which a compressible heat-exchange fluid is circulated by the compressor in one direction when operating in heating mode and in an opposite direction when operating in cooling mode, one of the heat exchangers forming the heating element.
 3. The heating system defined in claim 2, wherein the heat pump includes a fan for blowing a stream of air through the one heat exchanger serving as heating element and the radiator of the cooling-water system is between the one heat exchanger and the fan.
 4. The heating system defined in claim 2, further comprising means for extracting air containing waste heat from the rail car and passing it through the other of the heat exchangers.
 5. The heating system defined in claim 1, wherein the heating element is an electric heater. 